Simplify typehint in tool use test case (#95)

Also updated the Windows test target,
as Windows 2019 runners are going away

Author: ncoghlan

.github/workflows/test.yml

@@ -42,7 +42,7 @@ jobs:
       matrix:
         python-version: ["3.10", "3.11", "3.12", "3.13"]
         # There's no platform specific SDK code, but explicitly check Windows anyway
-        os: [ubuntu-22.04, windows-2019]
+        os: [ubuntu-22.04, windows-2022]
 
     # Check https://github.com/actions/action-versions/tree/main/config/actions
     # for latest versions if the standard actions start emitting warnings

tests/test_inference.py

@@ -245,7 +245,7 @@ def _append_fragment(f: LlmPredictionFragment, round_index: int) -> None:
         assert cloned_chat._messages == chat._messages
 
 
-def divide(numerator: float, denominator: float) -> float | str:
+def divide(numerator: float, denominator: float) -> float:
     """Divide the given numerator by the given denominator. Return the result."""
     return numerator / denominator